Yeah. When you install a new major OS, it's supposed to trigger a SMC reset and relearn the battery profile - which it sounds like it did for you on 10.9.

After calibrating it did indeed determine that, yes, you still had a failing battery.

I'm not quite in the same boat as you - my machine is a MacBook Pro 2008 pre-Unibody. But I've been through the "Service Battery" warning on this 5 year old machine before. And they were right! Chemically, the battery had degraded and could barely hold a charge for more than 25 minutes. The machine would power off randomly without the 10 minute "charge me now!" warning because the power curve was so bad, it could never predict I only had 30 seconds left.

Apple goes to great lengths to try to educate their consumers about how to protect the life of the batteries of their laptops:

http://www.apple.com/batteries/notebooks.html - Long term storage tips, maintenance tips, best practices, a little calendar reminder you can add to iCal to remind you to do these things, etc.

http://support.apple.com/kb/HT1446 - What you can do to increase your battery life, how to diagnose battery problems, etc.

10.9 itself! http://support.apple.com/kb/HT5873 - Click on the battery icon. It will tell you what processes are running right now that demand high power. The Activity Monitor has a new "Energy" tab showing per-process power utilization. At the bottom are various charts and statistics about your battery usage.

People abuse the hell out of laptop batteries by leaving the laptop connected to the charger all day, every day, like it was a desktop. They're perpetually 99%+ charged which stresses out the battery. The battery is meant to be used - use it!

And like you, I'm not experiencing the issues in this thread under 10.9.